The $20 million will be used to expand Portland's "Clean Energy Works" program, which provides low-cost financing to pay for retrofits that homeowners repay on their monthly utility bills. The goal is for monthly energy savings to offset the bulk of the financing cost, making efficiency upgrades painless.

The city seeded a pilot program with $2.5 million in block grant funds. So far, it has completed 72 retrofit loans averaging $11,000. Its not clear how much of the new money will go to Portland or other communities, but organizers said the ability to scale up statewide ultimately depends on their success in attracting private capital to fund the loans.